ROLE OF 5-HYDROXYTRYPTAMINE RECEPTOR SUBTYPES IN THE 1-[3-(TRIFLUOROMETHYL)PHENYL] PIPERAZINE-INDUCED INCREASE IN THRESHOLD FOR MAXIMAL ELECTROCONVULSIONS IN MICE

The effect of 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), a 5-hy droxytryptamine (5-HT) receptor agonist, on the threshold for maximal electroconvulsions was studied in mice. TFMPP in intraperitoneal (i.p. ) doses of 10, 20 and 40 mg/kg increased the convulsive threshold (the amperage necessary to produce the hindleg tonic extensor component of seizures in 50% of animals) by 28, 60, and 85%, respectively. The eff ect of TFMPP (20 mg/kg) was dose-dependently blocked by 1-(2-methoxyph enyl)-4-[4-(2-phthalimido)butyl] piperazine (NAN-190), prazosin, spipe rone, mesulergine, ketanserin, and ritanserin. On the other hand, pind olol and cyanopindolol had no effect on the convulsive threshold incre ased by TFMPP. The results indicate that the TFMPP-induced decrease in the susceptibility to seizures is connected to stimulation of 5-HT2 o r of both 5-HT1C and 5-HT2 receptors. Moreover, alpha(1)-adrenoceptors also appear to be engaged in this effect.